1. Field of the Invention
This invention relates to a method of recovering an optical disk substrate and an optical disk substrate recovering apparatus. More particularly, it relates to a method of recovering an optical disk substrate from an optical disk including a write-once optical disk called xe2x80x9cCD-Rxe2x80x9d, a read only disk called xe2x80x9cCD-ROMxe2x80x9d and an optical magnetic disk, and also relates to an optical disk substrate recovering apparatus for recovering the optical disk substrate from the optical disk.
2. Description of Related Art
Recently, a write-once optical disk called xe2x80x9cCD-Rxe2x80x9d is getting widely used for developing computer programs or recording account data in secret. For example, in a company developing computer programs, several hundreds of CD-Rs are used in one day.
However, since the majority of such CD-Rs include uncompleted programs or wrong data, they are to be disposed. Such a disk to be disposed may include confidential matter or data. Therefore, it is required to destroy the recorded data before disposing the disk so as not to leak out the confidential matter or data.
Japanese Unexamined Laid-open Patent Publication No. 09-097432 A (hereinafter referred to as xe2x80x9cJP"" 432) discloses a method of destroying the data of the optical disk. In the method, a coating material is applied on the recording surface of the optical disk, or a high power radiation is irradiated onto the disk.
Japanese Unexamined Laid-open Patent Publication No. 10-214424 A (hereinafter referred to as xe2x80x9cJP"" 424) discloses a method of making impossible to read the recorded data. In the method, the heat of 80xc2x0 C. to 150xc2x0 C. is applied to an optical disk to cause a thermal change around the periphery of the data pits.
Japanese Unexamined Laid-open Patent Publication No. 05-166231 A (hereinafter referred to as xe2x80x9cJP"" 231) discloses a method of making impossible to read the recorded data. In this method, taking into account of the poor adhesion of the reflection layer to the light absorption layer, an adhesive tape is adhered to the surface of the protective layer on the reflection layer and the upward force is applied thereto, by which the light absorption layer and the reflection layer are separated at the boundary thereof.
Furthermore, Japanese Unexamined Laid-open Patent Publication No. 05-210873 A (hereinafter referred to as xe2x80x9cJP"" 873) discloses a method of making impossible to read the recorded data. In this method, the recording layer is polished while supplying water thereto with a polisher consisting of a cylindrical polishing sheet manufactured by mixing grinding grains and an adhesive to a supporting material and molding the mixture by hot pressing.
However, according to the methods disclosed in JP"" 432 and JP"" 424, the disk with destroyed data still includes metallic films constituting the light absorption layer and the reflection layer made of aluminum and/or gold on the transparent disk substrate made of transparent synthetic resin. Therefore, disposing the disk as it is has problems in environmental safeguard because the plastic materials and the metallic materials are not separated. Furthermore, in order to re-use these optical disks, it is required to separate the optical disk into the synthetic materials of the disk substrate and the metallic materials of the reflection layer.
According to the method of JP"" 231, although the optical absorption layer as a recording layer and the reflection layer are separated with each other, the optical absorption layer is not separated from the disk substrate. Therefore, in order to recycle the synthetic resin disk substrate, It is required to remove the optical absorption layer from the disk substrate. Although the removal of the optical absorption layer from the disk substrate may not be technically difficult, the work is inefficient because the aforementioned removal of the optical absorption layer is performed in addition to the removal of the reflection layer.
According to the method of JP"" 873, since the polishing of the optical disk is performed while supplying water thereto, it is troublesome to treat the wasted water including the powder generated by polishing the optical disk as well as to extract noble metals which may be included in the reflection layer. Furthermore, it is required to protect the electric parts of the apparatus from water, which complicates the manufacturing of the apparatus.
The present invention is made in view of the aforementioned technical drawbacks.
It is an object of the present invention to provide a method of recovering an optical disk substrate from an optical disk and an optical disk substrate recovering apparatus, by which the data of the optical disk can be destroyed, the disk substrate can be recovered by removing the recording layer and the reflecting layer from the optical disk, and the powdered recording materials and reflecting materials can be easily treated.
According to one aspect of the present invention, a method of recovering an optical disk substrate from an optical disk having a recording layer and a reflecting layer laminated on the optical disk substrate made of synthetic resin by removing the reflecting layer and the recording layer included the steps of: abrading the reflecting layer and the recording layer of the optical disk into powdered reflecting materials and recording materials without supplying water to obtain an abraded disk substrate while collecting the powdered reflecting materials and recording materials, and collecting the abraded disk substrate.
With this method of recovering an optical disk substrate from an optical disk, the recording layer and the reflecting layer can be assuredly removed from the optical disk substrate made of synthetic resin to thereby recover the synthetic resin disk substrate to which no material constituting the recording layer and the reflecting layer is adhered. In addition, the abrasion of the optical disk is performed without supplying water thereto while collecting the powdered recording materials and reflecting materials, which enables an easy treatment of the powdered recording materials and reflecting materials.
Another aspect of the present invention resides in an optical disk substrate recovering apparatus for recovering an optical disk substrate from an optical disk having a recording layer and a reflecting layer laminated on the optical disk substrate made of synthetic resin by removing the reflecting layer and the recording layer. The apparatus includes an optical disk storing portion for storing a plurality of the optical disks, an abrader for abrading the reflecting layer and the recording layer of the optical disk into powdered reflecting materials and recording materials to obtain an abraded disk substrate, an optical disk transferring device for transferring the optical disk from the optical disk storing portion to the abrader one by one, a powder collecting device for collecting the powdered reflecting materials and recording materials, an abraded disk substrate storing portion for storing the abraded disk substrate, and an abraded disk substrate transferring device for transferring the abraded disk substrate to the abraded disk substrate storing portion.
With this apparatus, the recording layer and the reflecting layer can be assuredly removed from the optical disk substrate made of synthetic resin to thereby recover the synthetic resin disk substrate to which no material constituting the recording layer and the reflecting layer is adhered. In addition, by operating the apparatus after storing a plurality of optical disks into the optical disk storing portion, the optical disk substrates can be recovered automatically. Furthermore, by discharging the powdered reflecting materials and recording materials out of the apparatus, harmful influences to the motor due to the powdered materials can be prevented, resulting in a trouble-free operation of the apparatus.
It is preferable to absorb the powdered reflecting materials and recording materials by means of a vacuum pump, which causes air turbulence to thereby prevent a temperature rise of the disk substrate due to the friction heat generated during the abrasion of the optical disk.
It is preferable to agitate ambient air around the optical disk, which enhances the collection of the powdered reflecting materials and recording materials by the vacuum pump.
The optical disk transferring device and the abraded disk substrate transferring device may be independent devices or a common device. In a case where the optical disk transferring device and the abraded disk substrate transferring device are independent devices, the time required to recover the optical disk can be shortened. On the other hand, in a case where the optical disk transferring device and the abraded disk substrate transferring device are a common device, the structure can be simplified.